1. Field of the Invention
The present invention relates to a learning remote control device, a so-called "memory remote control", having a learning capability in which a remote-controlled signal can be stored in a memory after such remote-controlled signal has been received and analyzed and can be reproduced for transmission on the basis of data stored in the memory.
2. Description of the Prior Art
In the memory remote control device, the remote-controlled signal is received and analyzed for conversion into data which are subsequently stored in a memory. According to the prior art as shown in FIG. 15, the remote-controlled signal received by a photodiode 1 is supplied to a wave shaping circuit 2, having a one-shot circuit built therein, by which the received remote-controlled signal is shaped into a pulse signal and also into an envelope signal from which a carrier wave has been removed on the basis of the pulse signal. These pulse and envelope signals are supplied to a microcomputer 3 which is operable to measure and calculate necessary data such as the frequency of the carrier wave of the received remote-controlled signal, etc., on the basis of the pulse and envelope signals for storage into the memory.
Generally in the memory remote control device, a logic determination of digital data "0" and "b 1" is carried out in reference to a period between the set-up and set-down timings of the pulse of the received remote-controlled signal. However, in some European countries, as shown in FIG. 16, a unique logic determination is employed in which the set-up and set-down timings of the pulse signal within a predetermined time T are deemed to be "1" and "0", respectively and, where such unique logic determination is employed, there is available two type of remote-controlled signals; one being the remote-controlled signal modulated by the carrier wave and the other being the remote-controlled signal having no carrier wave.
FIG. 17 illustrates waveforms of various signals used for the explanation of the operation in which the remote-controlled signal modulated by the carrier wave in the environments in which the above described unique logic determination is employed is analyzed by the prior art memory remote control device of the construction shown in FIG. 15. In this figure, FIG. 17(A) represents a logic of the received remote-controlled signal; FIG. 17(B) represents the received remote-controlled signal; FIG. 17(C) represents an enlarged view thereof; FIG. 17(D) represents the pulse signal shaped into a pulse by the wave shaping circuit 2; FIG. 17(E) represents the envelope signal from which the carrier wave has been removed; and FIG. 17(F) represents a remote-controlled signal which has been reproduced.
In the wave shaping circuit 2 having the one-shot circuit built therein, the pulse signal having a predetermined pulse width as shown in FIG. 17(D) is outputted on the basis of the set-up timing of the received remote-controlled signal shown in FIG. 17(C) and the envelope signal shown in FIG. 17(E) is also outputted when the envelope signal sets up in synchronism with the set-up timing of the pulse signal and sets down when the pulse signal is not present during a predetermined period .alpha..
As hereinabove described, while the wave shaping circuit 2 detects the set-up timing of the received remote-controlled signal, the set-down timing corresponding to the logic "0" of the remote-controlled signal tends to be detected as the set-up of the carrier wave because of the presence of the carrier wave, which is subsequently converted into data. Therefore, it can be processed and treated as is the case with a remote-controlled signal which has been modulated according to a pulse position modulation (PPM) scheme such as generally employed in Japan.
In other words, the microcomputer 3 calculates the number N of pulses during a high level period of the envelope signal, measures one cycle period t1 of the envelope signal and a low level period t2 of the envelope signal and calculates the frequency f of the carrier wave according to the following equation on the basis of these data. EQU f=(N-1)/(t1-t2-.alpha.)
The data including the frequency of the carrier wave of the remote-controlled signal so analyzed are stored in the memory and, on the basis of the data so stored in the memory, the remote-controlled signal can be faithfully reproduced for transmission as shown in FIG 17(F).
On the other hand, FIG. 18 illustrates waveforms used for the explanation of the operation in which the remote-controlled signal has no carrier wave in the environments in which the above described unique logic determination is employed. In this figure, FIG. 18(A) represents the logic of the received remote-controlled signal; FIG. 18(B) represents the received remote-controlled signal; FIG. 18(C) represents a pulse signal which has been shaped into a pulse by the wave shaping circuit; FIG. 18(D) represents the envelope signal; and FIG. 18(E) represents a remote-controlled signal which has been reproduced.
In such case, since there is no carrier wave, the set-down timing corresponding to the logic "0" of the remote-controlled signal will not be detected and, therefore, the remote-controlled signal reproduced will be an erroneous one as shown in FIG. 18(E).
In the prior art memory remote control device in which the set-up timing of the remote-controlled signal is detected for the conversion into the data, there is a problem in that no remote-controlled signal can be accurately reproduced where the remote-controlled signal has no carrier wave employing the unique logic determination in which the set-up and set-down timings of the pulse signal within the predetermined period T are deemed to be logic "1" and logic "0", respectively, such as employed in some European countries.
Also, generally in the learning remote control device, during a storage mode in which a remote-controlled signal from a remote control device to be learned (which device is hereinafter referred to as "to-be-learned remote control device" is to be stored, a key of the to-be-learned remote control device to be stored is manipulated, and the learning remote control device receives and analyzes the remote-controlled signal transmitted from the to-be-learned remote control device in correspondence with the above mentioned key for the temporary storage in the memory. Subsequently, the same key of the to-be-learned remote control device is again manipulated, and the learning remote control compares the second received remote-controlled signal with the first received remote-controlled signal stored in the memory and finally stores the second received remote-controlled signal as a properly inputted signal in the event that the first and second received remote-controlled signals coincide with each other, thereby completing the storage.
Thus, in the prior art learning remote control device, the storage takes place when the first and second received remote-controlled signals coincide with each other and, therefore, it is necessary for a remote-controlled signal of identical code to be transmitted each time a key is manipulated.
On the other hand, the remote-controlled signal employed in some European countries includes such a remote-controlled signal in which, each time a key is manipulated, a particular bit varies, that is, the third bit from the beginning of a remote-controlled code varies in such a manner, 0, 1, 0, 1 . . . , each time a key is manipulated, and alternatively employ remote-controlled signal in which particular two bits vary, that is, the first and second bits from the beginning of the remote-controlled code vary in such a manner, 00, 01, 10, 11, 00, 01, 11, 00 . . . .
With these remote-controlled signal, since the code of the remote-controlled signal varies each time the key is manipulated, and therefore, in the prior art learning remote control device designed to store the signal when the first and second received remote-controlled signals coincide with each other, there is a problem in that no signal can be stored.